Composite millstone



(No Model.)

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UN rTnD STATES PATnNT Ormes.'

THOMAS L. STURTEVANT, OF FRAMINGHAM, ASSIGNOR TO TIIE STURTEVANT MILL COMPANY, OF BOSTON, MASSACHUSETTS.

COMPOSITE NIELLSTONE.

SPECIFICATION forming part of Letters Patent No. 452,958, dated May 26, 1891.

Application filed September 29, 1890. Serial No. 366,555. (No model.)

To all whom it may concern:

Beit known that I, THOMAS L` SrURrnvAN'r, a citizen of the United States, residing in Framingham, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Composite Millstones, of which the following is a specification.

My invention relates to composite mill- Io stones of the class in which corundum or emery is combined with cement or fusible material. As the skirt of the stone traverses a greater space in a given time than the eye, the former portion of astone of uniform consistency Wears much more rapidly than the latter, requiring frequentcutting down of the eye part of the stone.

The objects of my invention are to secure a millstone in which the grinding material will zo be firmly embedded or grasped to insure the wearing of the eye coincident] y with that of the skirt, to facilitate the proper dressing of the stone, and the manner of building up or constructing it. These ends I attain, iirst, by constructing the skirt of the stone of lumps or fragments of em ery embedded in cast-iron second, by combining with such a stone an eye of material softerthan the emery, such as iron or stone; third, by combining with such 3o a millstone metal strips inserted in its face in lines radial or tangential to its eye corresponding with the usual furrows; fourth, by constructing a stone of sector-shaped sections of cast-iron andlumps of emery encom-A 3 5 passed by a circumferential band or inclosin g ring.

The subject-matter claimed is hereinafter specified.

The accompanying drawings lshow composite millstone embodying my invention in the best way now known to me. Some of my improvements may be used without the others and in stones differing in composition and details of construction from those herein shown. Unless otherwise specified, the parts are of usual well-known construction and organization.

Figure' l represents a face view of the completed stone; Fig. 2, a transverse section 5o therethrough on the line 2 2 of Fig. l; Fig. 3,

a face view of the skirt of'the stone. Fig. 4; shows a View of sections of which the eye of the stone may be composed, the sections being radial, but the furrows tangential to the eye; and Fig. 5 shows a plan of aseetor or 55 skirt-section tangential to the eye, with appropriate furrow-pieces on each side thereof.

I preferably carry out my invention in the following manner: A circular band or hoop A, of metal, preferably of iron, is placed on a 6o at plate of similar metal as a former for the face of the stone. A dry sand core, a counterpart of the form of the eye C, is placed on the plate coneentrically with the band, the space between which and the core is filled with lumps 6 5 or fragments of emery of the desired size to the depth the stone is designed to wear and packed or gently rammed to settle the parts in the desired relation. Before doing this, however, suitable patterns to form spaces 7o for the accommodation of former pieces or strips D are laid on the face-plate above mentioned. Melted iron is then poured over the emery, llin g the interstices or spaces between its fragments and covering the surface to a suitable depth. The iron in cooling' contracts, thus filling all the interstices and holding each fragmentof elneryiirmlygrasped. The sand core is then removed, leaving a space into which material softer than the emery-such as 8o iron, burr, or Esopus stone-is placed to form the eye portion of the stone. Furrows d, it will be observed, are cut in the eye portion of the stone to receive the furrow-strips D, heretofore mentioned. 8 5

The grinding portion of the stone need not be the full thickness of the band; but it is backed with cement B or other heavy material, or iron plates may be bolted thereon to secure the desired weight. o

The furrow-strips D can be held in place by being inserted in suitably-shaped grooves formed in the face of the stone, as hereinbefore explained, or in other well-known Ways.

The eye portion of the stone is provided 95 with lugs c, interlocking with similar grooves c in the skirt E to lock the eye and skirt together securely.

I have described the skirt of the stone as formed in a single piece. roo

Fig. 5 shows a sector-shaped section E', one of a series which serves to make up the stone, these sectors being formed in the way above described and adapted to receive furrow-strips D. These sectors and furrow strips are clamped together in position by means of the circumferential band A, secured upon the periphery of the stone by shrinking or in other Well-known ways.

Fig. 1i shows the eye portion of the stone as composed of sections C C2, which may replace the solid eye-piece hereinbefore described.

Under the organization above described, the eye portion being softer than the skirt will Wear away more rapidly, and thus keep the face of the stone true. The furrow-pieces, being softer than the emery, also wear away more rapidly, but can readily be resharpened by proper tools or removed and replaced by fresh pieces.

I do not claim herein the method of casting the stone, but limit myself to the details of construction and organiz-ation herein claimed, as said process constitutes the subject-matter of another application filed simultaneously herewith, Serial No. 366,554.

The details of construction of another compound millstone,analogous in some respects to the one herein claimed, but differing therefrom in essential particulars,'constitute the subject-matter of another simultaneouslyled application,Serial No. 366,556.

I do not broadly claim herein making the eye of the millstone of material softer than that of the skirt, as this is old, but limit 1n yself to the organization specified in the claims.

What I claim as of my own invention is- 1. A millstone consisting of the combination of small lumps of emery having spaces or interstices intervening between them and cast-iron interposed between the lumps and filling said spaces.

2. A millstone consisting of the combination of a skirt of broken lumps of emery embedded in cast-iron and an eye of material softer than the emery.

A millstone consisting of the combination of a skirt composed of small lumps of emery embedded in cast-iron and an iron eye formed with projections on its periphery interlocking with the skirt.

4. A millstone consisting of the combination, substantially as hereinbefore set forth, of emery embedded in cast-iron and furrowstrips of metal also embedded therein.

5. A millstone consisting of the combination, substantially as hereinbefore set forth, of emery fragments embedded in cast-iron, constituting the skirt of the stone, an eyepiece of softer metal, and metal furrow-strips embedded in both the eye-piece and skirt.

G. A millstone consisting of the combination of a skirt composed of a number of separable sections, each made up of small lumps of emery embedded in cast-iron, an eye, and an inclosing ring.

7. A millstone consisting of the combination, substantially as hereinbefore set forth, of a skirt of emery embedded in cast-iron, a separate eye-piece, and metal furrow-strips secured in the face of the stone.

8. A millstone consisting of the combination of a number of separable skirt-sections composed of small lumps of emery embedded in cast-iron, separable eye-sections of softer material inclosed therein, and a circumferential band or inclosing ring.

9. A millstone consisting of the combination, substantially as hereinbefore set forth, of skirt-sections of emery embedded in castiron, eye-sections inclosed therein, furrow.

strips secured to the face of the stone, and a circumferential band or inclosing ring.

In testimony whereof I have hereunto subscribed my name.

THOMAS L. STURTEVANT.

Vitnesses: p

W. H. ELLIS, F. E. CLEARY. 

